After drawing an ABG sample, you notice that the blood appears to be darker in color. You suspect that obtained sample is actually venous blood. Which of the following would be the best way to confirm this suspicion?

In general, sometimes an inexperienced practitioner can accidentally stick a vein instead of the artery when trying to obtain an ABG sample. When this occurs, the venous blood isn’t oxygenated, so it has a darker appearance compared to the bright red arterial blood.

In this case, the best way to confirm that the sample is venous blood is to cross-check the results against the patient’s SpO2. Because, when you run the results, the oxygenation values are going to be falsely low, again, since venous blood is not oxygenated.

You can check the patient’s oxygen saturation with a pulse oximeter to see if it matches the results of the blood sample. Of course, if it is in fact venous blood, there won’t be a match.

None of the other answer choices really make sense in this situation so we know that the correct answer has to be D.

 The correct answer is: D. Cross-check the results against the patient’s SpO2